Danish security personnel check travellers IDs at the train station in Kastrup, outside Copenhagen, on January 4, 2015

Stockholm (AFP) - The number of migrants arriving in southern Sweden from Denmark dropped sharply on the first day that Sweden imposed systematic ID checks on travellers, police said Tuesday.

Police in the southern Swedish region of Skane said they had registered just 48 migrants arriving in Sweden on Monday. Excluding New Year's Day, there had been at least 200 per day since December 29.

"One can say that it's a sharp drop. But it's only been one day (since the controls were introduced), and we can't exclude that refugees will find other ways of entering Sweden," police spokeswoman Ewa-Gun Westford said.

Sweden -- which has taken in more asylum seekers per capita than any other EU nation -- recently said it could no longer cope with the unregulated flow of arrivals.

In a bid to stem the influx, it has since Monday required all travellers to show photo identification when entering from Denmark, the main entry point for migrants hoping to start a new life in Sweden.

The Swedish coast guard said it was prepared for the possibility that migrants may now try to clandestinely cross the Oresund strait that divides Denmark and Sweden.

"We have to be prepared for the fact that people may seek other routes than the (Oresund) bridge or ferries, regardless of whether it is a Danish network behind this or individual initiatives," coast guard spokesman Mattias Lindholm told news agency TT.

Sweden has yet to officially register any migrants arriving on clandestine boats across the Baltic.

- 'A second Mediterranean' -

But Eliot Wieslander, executive director of the Swedish branch of Medecins du Monde, said that clandestine boat crossings and illegal entries were very real worries.

"The thing that we fear most is that the Oresund will become a second Mediterranean," she said.

"It's not the same amount of people as the Mediterranean. But we've already had reports that people are going to try to cross in unregistered boats," she said.

The worry, according to her, and also to Sanna Vestin, the director of the Swedish Network of Refugee Support Groups, is that if Europe does not adequately address the problems of conflict and flight, then people will continue to risk their lives to seek asylum in Europe.

"They don't want to die and they don't want to watch their families die. If you tell them no, then they will take illegal routes," said Vestin.

Illegal entry, Vestin and Wieslander agreed, also creates other problems.

"There will be a whole new market for smugglers and traffickers in Sweden and Scandinavia -- because people, at the end of the day, want to be with their families in a safe country," said Wieslander.

In early December, an inflatable dinghy was discovered on the shores of the southern town of Skillinge and it raised suspicions of clandestine crossings, but border police said it was "very unlikely" the boat had been used for that purpose.

The introduction of systematic identity checks by Sweden on Monday prompted Denmark to introduce random checks on its border with Germany, causing concern in Berlin.

On Tuesday, the European Commission responded by inviting ministers responsible for immigration in the three countries to a meeting Wednesday in Brussels.